Variable pitch screw propeller



Aug. 28, 1945. G. BAXTER VARIABLE PITCH SCREW PROPELLER Filed Feb. 10, 1944 INVENTOR, ewyz Bax/e2:

iffy/714% lll Patented Aug. 28, 1945 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to improvements in variable pitch screw propellers and has particular reference to a variable pitch propeller suitable for use on an outboard motor.

The principal object of this invention is the provision of a variable pitch propeller whereby the propeller blades may be manually adjusted to different pitch positions for changing the speed of the boat without varying the speed of the motor, and also for reversing the drive whereby the boat may be driven in the reversed direction.

Another object of the present invention is the provision of a device of the character described having propeller blades screw-threaded for pitch adjustment in a hub.

A further object of this invention is the provision of a variable pitch propeller provided with a split propeller hub whereby the blade mountings are adjustable to compensate for wear.

A still further object is the provision of means for automatically securing the motor shaft from vertical oscillation when the blades are adjusted to the reverse pitch.

Other objects are simplicity and economy of construction, ease and efiiciency of operation and adaptability for use with the various types of outboard motors without any material change in their construction.

Further objects will appear during the course of the specification referring to the drawing wherein:

Figure 1 is an elevational view partly in section of an out-board motor embodying the invention.

Fig. 2 is an enlarged sectional view of the propeller hub and associated parts.

Fig. 3 is a plan view of the hub shown in Fig. 2.

Fig. 4 is a sectional view taken on line IVIV of Fig. 2.

Fig. 5 is a sectional view taken on line V-V of Fi 4.

Fig. 6 is an enlarged, fragmentary, sectional view of the propeller blade mounting in the hub.

Throughout the. several views like reference characters refer to similar parts and the numeral l0 designates a boat body on which the out-board motor I2 is mounted to provide propulsion means for the boat. The tubular post l4 which carries the motor drive shaft 16 is provided adjacent its upper end with a collar i8 and is secured to turn and held against axial displacement upon a hub 20 depending from the crank case 22 of the motor 24. Collar I8 has a side projection 26 through which is formed a slot 28 to receive the flat operating lever 30. Lever 30 has free movement up and down and longitudinally but snugly engages the side walls of the slot 28 so as to cause a rotation of the collar l8 and tube l4 for steering the boat. Mounted at 32 upon tube I4 is an under water unit 34. By swinging the lever 5 30 sideways the fin or rudder 36 is adjusted to steer the boat and propeller 38 is swung to different pitches by sliding the control lever longitudinally in slot 28. The lower edge of lever 30 is notched at 40 to receive the detent 42 carried by collar I8 to secure the lever against accidental longitudinal movement.

The upper motor head of the device is provided with a bracket 44 which is pivoted at 46 to a clamp member 48 attaching the apparatus to the boat III. The entire motor and tubular post are oscillatable about the pivot 46 for clearing the under water unit of obstructions, etc.

Driven shaft I6 is provided at its lower extremity with a. bevelled gear 50 which intermeshes with a bevelled gear 52 mounted on the propeller shaft 54 disposed at right angles to shaft l6 thus providing means for driving the propeller shafts and parts associated therewith. Mounted on the outer extremity of propeller shaft 54 is a transversely split hub 56 comprising two sleeve-like members 58 and 60 respectively which are spaced apart by shims 62 and secured together by machine screws 64 as clearly shown in Fig. 5.

Radially disposed holes 66 are formed in the split hub 56 at the juncture of the hub members 58 and 60 so that substantially half of the hole or recess is formed in each of said members. The outer portion of holes 66 are enlarged at 68 as clearly shown in Figs. 2 and 6 and the inner portion of said hole is threaded at 10.

The propeller blades 12 are of any of the conventional types provided with a novelly constructed stem 14 by means of which they are adjustably mounted in hub 56. Adjacent the 40 blade of the propeller blade is an annular flange 16 which is adapted to fit into the enlarged recess 68 to rest against a resilient cushion member 18. The outer extremity of the propeller stem is threaded at 80 to operatively engage threads 10 of the hub. This threaded bearing for the oscillatable propeller blade presents a much larger bearing surface than could be obtained by the ordinary pivotal type of bearing. As the propeller blade is adjusted to the desired variable pitch, the stem 14 will move radially a fractional part of the pitch of the thread 80 and the resilient cushion will allow for such movement and maintain a definite seal to prevent the water from entering the adjusting parts. Should the threads become worn by long use, the hub 54 to permit free adjustment of the propeller.

blade. Slidably mounted on the outer extremity of hub member I. is a sleeve 02 having a reduced end portion ll grooved at l to receive pins ll positioned in the bifurcated ends I of a lever arm 82 which is secured at its upper end by pivotal pin 94 to operating lever 3|. lever I2 is pivoted intermediate its ends at 98 to arm I. which is secured to oscillate with tubular post ll.

Referring to Fig. 1, it will be observed that when the operating lever 3. is moved longitudinally, it. will cause sleeve .2 to slide on hub member I! which is secured against movement relative to propeller shaft It by means of set screw ill, Sleeve 82 is provided with axially extending arms I02 and it. These arms are slotted at I" to receive pin I08 mounted in the face of annular flange Ii which isintegral with the propeller blade.

Referring to Fig. 3, it will be noticed that the arms Ill and I are disposed on opposite sides of the axes of the diametrically opposed propeller blades so that as the sleeve 82 is moved inwardly, the propeller blades will be oscillated in opposite directions whereby the pitch of the blades will be varied simultaneously in opposite directions but 7 through like angles. Due to the fact that the blades rotate in the opposite direction, the upper blade in Fig. 2 will be provided with a right hand thread while the lower blade will be provided with a left hand thread. This threaded movement will maintain the blades in identical radial positions at all times regardless of the pitch. Since the pin ill moves in an arcuate path, it will travel in the slot iii of the arm a short distance. How ever, since the degree of oscillation is relatively small, this distance of travel will not be objectionably long. When the blades are reversed to cause a backing of the boat, it is found necessary to provide means for automatically securing the tubular post ll against oscillation. This is accomplished by means of a lever ill pivoted intermediate its ends at ii! to the tubular post it, the outer end ofsaidleverhavinaaslotiildisposedatanangle tothetravelolleverarmllandadaptedtoreceive theguldepinlltcarriedthereby.

The inner end ill of lever Ill is notched at ill. Thisnotch illisalwaysmaintainedinreglater with a detent in integral with clamp memcillatlonofthelll rtt- Alll nl III secured at its.

oneendtoarmllandatiuotherendtotheinner end lll'oflever ill serveatomaintain theselatch- 1% against rattle or accidental latching.

1. In a device of the character described a driven propeller shaft, a transversely split hub securedtosaldshafhandhavingthepartsthereof secured together with shims therebetween and having threaded radial holes centered between said hub parts, propeller blades having flanged threaded pivot stems operatively mounted in the threaded holes of said hub, a rubber gasket posi tioned under compression between the flange of each of said stems and the hub, and manually operable means to simultaneously pivot said stems whereby the pitch. of said propeller blades is varied.

2. In a device of thevcharacter described the combination with a hingedly mounted tubular post having amotor at itsupper end and an under watei-unit at its lower end. a propeller shaft journaled in said under water unit, a shaft extending from said motor throughsaid tubular post to drive said propeller shaft, of a plurality of propeller blades having threaded pivot stems mounted for helical adjustment in a hub carried by said propeller shaft, manually operable means to simultaneously adjust and vary the pitch of said propeller blades, and means operable by said manually operable means to secure said tubular post against hinsins.

GEORGE BAXTER. 

